Engineered Screwjacks?

[Greg Steckler]

Does anyone know of a catalogue of sizes, loads, singles, doubles, 4-ways from a mfg. who produces engineered screwjacks?

[Kyle - Utah]

Hello Webmaster,

U.S. Screwjack Distributor (http://www.powerjacks.com/)
AutoCad Screwjack Specifications & Diagrams (http://www.hpceurope.com/vgb/dxf/Screwjacks/)
Free VoloView Express CAD Viewing Utility (http://usa.autodesk.com/adsk/index/0,,837403-123112,00.html)

You will likely note that lifting capacities are rated in Newtons rather than in Pounds. A Newton translates to .2248 Pounds of force. This means that a 200kN screwjack can lift up to roughly 22.5 tons. (This is about the upper limit for machine screw screwjacks. Ball screw screwjacks max out at about 56 tons.)

With that said, I am curious to know why you would prefer screwjacks over hydraulics. Both are designed for temporary-only use and hydraulics provide much greater lifting power with less effort and expense. Screwjacks are primarily used, at least in the industrial setting, for precision lifting and linear adjustments.

Enerpac, Parker, and a host of other manufacturers produce high quality hydraulic rams that are (IMO) much more cost effective than the use of screwjacks. They may also be connected in parallel to offer uniform lifting over a large span. A used 25 Ton hydraulic ram with a 6" stroke might sell in the $300 range, whereas a used machine screw screwjack might sell for $800 and a used ball screw screwjack might sell at around $2,200 (The difference in the two screwjack styles is in the mechanics and internal safety features of the actuators). Perhaps the most useful information to the 'average man on the street' is that most rental centers will rent hydraulics but I don't know of a single one that will rent screwjacks.

Best Regards

[blue eyed devil]

WHAT! Hydraulics for settling jacks? What are you building,Kyle?
The Kansai International Airport?
Can't help you on that one Greg, but I would contact Schroeder for the companies they carry.

[Greg Steckler]

Blue:
I saw this very screwjack at the Portland Log Home Trade Show yesterday...very attractive in copper coating but I forgot to ask Tracy of The Log Home Store what her price was on it. Schroeder wants $82.50 and I imagine Tracy must have it priced similarily. It is rated at 20,000 lbs. At that load you have to really worry about the material above and below and how thick the plates are. Also, some Building inspector is bound to say, "Where is the ICBO number/report?".

Kyle:
Your links are great for UK engineered stuff and I'm sure they would be fine in the US as the company sells world wide. These are undoubtably engineered with ICBO or eqivalant numbers. Betcha' price is up there tho'. FYI, Kyle, in handcrafted log building these settling screwjacks are permanent. They should be expected to hold the load for a couple of centuries at least. My engineer in Boulder has spected out the screwjacks (threads, plate, nut sizes)(27 of them!) for the Willamette as it goes to Grand Lake, CO with 70 lb. snow loads but that prompted me to ask about "off the Shelf" engineered screw jacks, their availablility, price, sizes, etc. Thanks all!:)

[Kyle - Utah]

Hello Webmaster,

Originally posted by Greg Steckler
FYI, Kyle, in handcrafted log building these settling screwjacks are permanent. They should be expected to hold the load for a couple of centuries at least.

My ignorance in this area certainly shows through with this one. I was told that Acme Screw Threads were not designed for permanent loads. Then again, the application that I wanted to use them in was holding up a 50 Ton milling machine. I was forced to cast a concrete and rebar base to meet local code. The inspector that I spoke with was very deliberate in his statements that Acme threads are wonderful for high torque applications but that they fail over a relatively short period of time. (Something to do with the steep angle of the box-like thread tearing from the shaft over time from vibration while under a full load.)

Anyway, I am glad that you found what you were looking for. I am also glad to know that screwjacks are acceptable in log home building. A nice long shaft up through several courses of logs would allow for easy adjustments without the need for reinforced steel pillars set in concrete.

Best Regards